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Query: UNIPROT:P00750 (PLA)
 16,800 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Reactive low molecular weight poly(L-lactide) (PLA) is required to produce in situ hardened scaffolds with fast rate of crosslinking, high crosslink density, and adequate mechanical strength. The objective of this work was to synthesize unsaturated ultra low molecular weight PLA (ULMW PLA) as an injectable in situ crosslinkable macromer for biomedical applications. Low molecular weight PLA was synthesized by ring-opening polymerization of L-lactide (LA) using diethylene glycol (DEG) as the initiator. The molar ratio of the LA to DEG ranged from 5 to 20. Non-solvents methanol, ether, and hexane were used for purification and fractionation. The PLA samples that were precipitated in methanol and ether had narrow distributions (PDI=1.2) and resulted in a powder with M(n) of 4.8 and a wax with M(n) of 3.6 kDa, respectively. The PLA sample in which the supernatant from ether was re-precipitated in hexane produced a viscous ULMW PLA with M(n) and PDI of 1.2 kDa and 1.2, respectively. The ULMW PLA was reacted with fumaryl chloride to produce unsaturated in situ crosslinkable poly(lactide fumarate) (PLAF) macromer. Porous scaffolds were produced after injection and in situ crosslinking of the PLAF macromer with NVP crosslinker in the presence of a porogen. New bone was formed in the scaffold when it was implanted in nude mice which demonstrated that the scaffold was osteoconductive. PLAF is potentially useful as a reactive macromer in fabrication of bioresorbable injectable in situ crosslinkable scaffolds for tissue regeneration.
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PMID:Synthesis and characterization of bioresorbable in situ crosslinkable ultra low molecular weight poly(lactide) macromer. 1759 74

In situ crosslinkable biomaterials with degradation profiles that can be tailored to a particular application are indispensable for treating irregularly shaped defects and for fabrication of shape-selective scaffolds. The objective of this work was to synthesize ultra low molecular weight functionalized PLA and PLGA macromers that can be grafted with bioactive peptides and crosslinked in situ to fabricate biodegradable functional scaffolds. In situ crosslinkable lactide-co-glycolide macromer (cMLGA; "c" for crosslinkable, "M" for macromer, and "LGA" for lactide-co-glycolide) was synthesized by anionic polymerization of lactide and glycolide monomers followed by condensation polymerization with fumaryl chloride. The cMLA (100% L-lactide) and cMLGA macromers formed porous crosslinked scaffolds with NVP as the crosslinker. The mass loss of the crosslinked cMLA and cMLGA was linear with incubation time in vitro (zero-order degradation) and the degradation rate depended on the ratio of lactide to glycolide. cMLGA scaffold with 1:1 lactide to glycolide ratio completely degraded after 4 weeks while the cMLA lost less than 40% of its initial mass after 35 weeks. When cMLA scaffold was functionalized with acrylated integrin-binding Ac-GRGD amino acid sequence, bone marrow stromal (BMS) cells attached and spread on the cMLA scaffold and exhibited focal-point cell adhesion. The mRNA expression levels of collagen-1alpha, osteonectin, and osteopontin for BMS cells seeded in the scaffolds with 1 and 5% Ac-GRGD were upregulated compared with those without Ac-GRGD. cMLGA is attractive as in situ crosslinkable macromer for fabrication of functional scaffolds with degradation characteristics that can be tailored to a particular application.
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PMID:Material properties and bone marrow stromal cells response to in situ crosslinkable RGD-functionlized lactide-co-glycolide scaffolds. 1843 54

Glycopolymer-corona-based micelles are obtained in a one-pot procedure, through reaction of D-mannosamine or D-glucosamine with the N-succinimidyl (NS) esters of a poly(D,L-lactide)-block-poly(N-acryloxysuccinimide-co-N-vinylpyrrolidone) (PLA-b-P(NAS-co-NVP)) amphiphilic copolymer (presenting quasi-alternating NAS/NVP units) in dimethyl sulfoxide (DMSO), followed by nanoprecipitation and dialysis against water. The glycopolymer micelles exhibit a higher CMC and size than those obtained from unmodified copolymer, due to increased hydrophilicity of the external block as a result of sugar derivatization, and the availability of the sugars at the micelle surface is evidenced through interactions with Concanavalin A (Con A) lectin, as attested by turbidimetric measurements and enzyme-linked lectin assay (ELLA). Interestingly, the glycopolymer micelles can be further used for hydrophobic molecule encapsulation and release, as shown with imiquimod, while keeping their interactions with con A intact. It is concluded that the PLA-based amphiphilic/reactive copolymer represents a versatile platform for glycopolymer-based micelle constructs for drug/vaccine delivery.
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PMID:Elaboration of glycopolymer-functionalized micelles from an N-vinylpyrrolidone/lactide-based reactive copolymer platform. 2382 39